JP5921867B2 - Method for producing an elastic composite having a fiber surface - Google Patents

Description

The present invention relates to a method for producing an elastic composite having a fiber surface.

Elastic composites having a fiber surface are used in particular for producing, for example, tapes or elastic backsheets for baby diapers, incontinence products, feminine hygiene products and the like. When these are applied, the fiber surface that needs to be manufactured at low cost is important. In this case, the fiber surface should not impair the elasticity of the film.

A composite material composed of an elastic support film and a laminated nonwoven material is known. The nonwoven material constitutes a rigid structure that has a decisive influence on the stretch properties of the composite. Therefore, a composite consisting of an elastic support film and a laminated nonwoven material must be mechanically activated by locally stretching after the lamination process.

From US Pat. No. 6,057,049, a method is known for producing an elastic composite with a fiber surface in which a layer of meltblown nonwoven is formed and adhered to an elastic film without pre-strengthening. In this method, the nonwoven fabric layer is not wound and unwound, and the nonwoven fabric layer is not guided under a tensile stress. Therefore, the nonwoven fabric layer can be configured to have a low strength and particularly a small unit area weight, and does not strongly hinder the elastic expansion and contraction of the composite material. Thus, this composite does not require subsequent mechanical activation. However, the bond strength between the fibers of the fiber layer and the elastic film is not yet satisfactory. Since it is processed to have sufficiently unfixed fibers, it is not guaranteed that all fibers are sufficiently fixed in the adhesive matrix. The fiber may unintentionally peel from the joint and be removed by the user.

European Patent Application No. 2 177 654

From this technical background, the problem underlying the present invention is accentuated by the high expansion capability, the fiber surface is free of non-fixed fibers not peeled from the bonded portion during use of the composite, the composite having a fiber surface It is to provide a method for manufacturing a material.

The solution of the object and problem of the invention is the method according to claim 1. In the method according to the present invention, first, a laminate comprising an elastic cover layer and a core made of a nonwoven material is produced. This laminate is then separated into two strips, each comprising a cover layer and an adhesive layer of nonwoven material, by tearing the core. This method, fibers of the fiber surface, is constrained to the nonwoven material, when tearing the core consisting of non-woven material, having the benefit of the free fibers which readily peeled from the coupling portion does not occur. A slightly reinforced nonwoven material is used. The degree of strengthening is, for example, when applying calendering strengthening, so that the composite material can elastically stretch without mechanical activation later, and the stretch properties are affected by the elasticity of the cover layer. Can be adjusted.

  In order to separate the laminates, the strips are pulled apart by holding them separately and applying tension, in particular. The strip can be guided through a driven roll and wound up separately. Within the scope of the present invention, the separation process is coupled with the mechanical activation of the elastic cover layer of the strip, which is coupled by the expansion and contraction of the elastic cover layer upon ejection. Upon discharge and winding of the strip, the strip can be stretched laterally and / or longitudinally by suitable equipment. In particular, the strip can also be guided through a profiled roll that overstretches the strip transverse to the discharge direction. As a result, the expansion / contraction characteristics of the composite material can be influenced and further improved.

The tearing of the nonwoven material can be assisted by a cutter disposed on the separation surface.

A laminate having an elastic cover layer and a core made of a nonwoven material can be manufactured by various methods. In particular, the nonwoven material is laminated between two elastic film webs constituting the cover layer . However, an extrusion-type lamination in which an elastic layer is formed on a nonwoven material by extrusion is also conceivable.

The elastic cover layer in particular has a layer thickness of 20 μm to 100 μm and may consist of a styrene-block-copolymer or a thermoplastic polyolefin-elastomer. In addition to a monofilm, a film that is coextruded in multiple layers can also be used. In particular, perforated or breathable elastic films are also conceivable for the cover layer. This characteristic, which is important for composites, is obtained when a breathable elastic film is used. Instead of an elastic film, basically an elastic nonwoven material with a sufficient tensile strength can also be used.

The nonwoven material and the elastic film web or elastic cover layer are in particular bonded together, in particular polyurethane adhesives and hot melt adhesives being suitable. The adhesive can be applied in a planar shape or a pattern, for example, in the form of dots. Preference is given to the application of planar adhesives, when using a single component polyurethane adhesive without solvent (1-K-PUR), the adhesive application is from 1 g / m ² to 2. A coating amount of 5 g / m ² is sufficient. When using hot melt adhesives, ^generally, higher coating weight of 3g / ^{m 2} ~5g / m 2 is required.

The nonwoven material that constitutes the core of the laminate and is torn in the course of the manufacturing method is in particular composed of a meltblown nonwoven fabric. Melt blown nonwoven fibers are produced by extrusion and usually flow out from a plurality of holes arranged side by side in an extrusion nozzle. Immediately after exiting the extrusion nozzle, the molten liquid polymer strand flowing out of the hole is stretched by the action of compressed air. The meltblown fibers stand out by being very thin and guaranteeing a uniform and good cover of the elastic cover layer, even with a small unit area weight, and having a particularly soft appearance. The nonwoven fabric consists in particular of polyolefin fibers, in particular polypropylene fibers. Meltblown nonwoven fabric, for the process according to the invention, easily be ^enhanced, it can be used in a weight per unit area of ^{5g / m 2 ~20g / m 2} . For example, the degree of reinforcement by calendering reinforcement is adapted to the desired stretch properties of the composite.

As the nonwoven material, a multilayer nonwoven material having an SMS layer structure (spun-melt-spun) including an outer layer made of spunbonded nonwoven fabric (S) and an intermediate nonwoven fabric layer made of meltblown fibers (M) can also be used. . The combination of the spunbond nonwoven fabric and the melt blown nonwoven fabric gives the nonwoven fabric high strength in the flow direction (MD direction). When tearing a pre-strengthened laminate , the nonwoven material in the core layer made of meltblown nonwoven is separated. It has been determined that when the separation surface extends through a core layer made of meltblown nonwoven, the material thickness and unit area weight of the strip separated by tearing of the laminate is kept constant within narrow tolerances. A composite strip with a high quality, in particular a very high value fiber surface, results.

Other nonwoven materials can be used as well for the process according to the invention. However, for example, when a fluffy nonwoven fabric is used as the core layer of the laminate, the quality of the fiber surface is deteriorated.

  The composites produced by the method according to the invention are suitable for hygiene products, for example for baby diapers and parts of incontinence products or closure elements. Furthermore, so-called soft touch films for application outside the scope of hygiene products can also be produced by the method according to the invention.

  In the following, the invention will be described on the basis of a drawing illustrating only one embodiment.

1 schematically illustrates a method for producing an elastic composite having a fiber surface. FIG. 2 schematically shows a cross-sectional view of a laminate manufactured as a semi-finished product by the method illustrated in FIG. 1. FIG. 3 schematically shows the separation of the semi-finished product illustrated in FIG.

The method illustrated in FIG. 1 is useful for producing elastic composites with fiber surfaces that can be used as soft touch films or elastic elements such as baby diapers, incontinence articles and the like. In this method, in a first step, a laminate 1 including elastic cover layers 2 and 2 ′ and a core 3 made of a nonwoven material is manufactured as a semi-finished product. FIG. 2 shows the layer structure of the semi-finished product. The laminate 1 is then separated into two strips 4, 4 ′ each comprising a cover layer 2, 2 ′ and an adhesive layer made of nonwoven material 5. The strips 4, 4 'each constitute one process product that can be used as an elastic composite without subsequent mechanical activation.

The core 3 is made of a melt blown nonwoven fabric or has a multilayer structure having an outer layer made of a spunbond nonwoven fabric and an intermediate nonwoven fabric layer made of melt blown fibers. The nonwoven fabric web 6 constituting the core 3 is laminated between two elastic film webs 7 and bonded to the film web 7. The adhesive 8 is applied to the surface of the film web 7 adjacent to the nonwoven material, particularly in a planar shape. As the adhesive 8, a polyurethane adhesive or a hot melt adhesive can be used.

  The laminate 1 is separated into two strips 4, 4 ′ by tearing the core 3. The strips 4, 4 'are gripped separately and pulled apart by applying tension. According to FIG. 1, the strips 4, 4 ′ are guided through the driven roll of the discharge device 9 and are wound up separately. Optionally, the discharge device 9 can be combined with a stretching device that stretches the strips 4, 4 'laterally and thereby mechanically activates.

  The tearing of the core 3 can be assisted by the cutter 10 disposed on the separation surface.

Comparing FIGS. 2 and 3, it can be seen that the method according to the invention produces an elastic composite, ie a strip 4, 4 ′ comprising an elastic support and a fiber surface. The elastic support is composed of the cover layers 2 and 2 'of the laminate 1, and gives the composite material its mechanical properties. The fiber structure depends on the nonwoven material used for the core 3 of the laminate 1. It is preferable to separate a non-woven fabric layer composed of a melt-blown non-woven fabric that is thin and constitutes a high-value fiber surface during separation. In order to manufacture the laminated body 1 which comprises a semi-finished product, the lightly reinforced nonwoven fabric is processed. Separating the nonwoven fabric in a subsequent step does not produce free fibers that will peel off when the composite is used. When separating the nonwoven material core 3, strips 4, 4 ′ having a constant value within narrow tolerance limits with respect to the material thickness and its unit area weight are constructed.

DESCRIPTION OF SYMBOLS 1 Laminated body 2,2 'Cover layer 3 Core 4,4' strip 5 Nonwoven fabric material 6 Nonwoven fabric material web 7 Film web 8 Adhesive 9 Discharge device 10 Cutter

Claims (8)

In a method for producing an elastic composite having a fiber surface,
A laminate (1) comprising an elastic cover layer (2, 2 ') and a core (3) made of nonwoven material is produced, and this laminate (1) is then torn through the core (3) A method characterized in that it is separated into two strips (4, 4 ') each comprising a cover layer (2, 2') and an adhesive layer (5) made of nonwoven material.   2. Method according to claim 1, characterized in that the strips (4, 4 ') are gripped separately and pulled apart by applying tension.   3. A method according to claim 1 or 2, characterized in that the strips (4, 4 ') are guided through driven rolls and wound up separately.   4. A method according to any one of the preceding claims, characterized in that the tearing of the core (3) is assisted by a cutter (10) arranged on the separating surface. In order to produce the laminate (1), the nonwoven web (6) constituting the core (3) is laminated between two elastic film webs (7) constituting the cover layer (2, 2 '). A method according to any one of claims 1 to 4, characterized in that: 6. Method according to claim 5, characterized in that the nonwoven web (6) and the elastic film web (7) are glued.   7. The method according to claim 1, wherein the core (3) of the laminate (1) consists of a meltblown nonwoven fabric. For the core (3) of the laminate (1), a multilayer nonwoven material having an SMS layer structure is used, which is composed of an outer layer composed of a spunbond nonwoven fabric (S) and a meltblown fiber (M). A method according to any one of the preceding claims, characterized in that it comprises a central nonwoven layer.

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